TWO BIG ENDOSYMBIOTIC EVENTS. “Two distinct evolutions by bacterial endosymbiosis gave rise to eukaryotic realms. Firstly, proteobacteria developing to the mitochondria of all eukaryotic cells and secondly, cyanobacteria that changed to chloroplasts in plant evolution.”
http://mcb.berkeley.edu/courses/mcbc245/MCBC245PDFs/Jan31/Huettenbrenner2003.pdf